The present invention relates to contactless integrated circuits operating by inductive coupling and contactless integrated circuits operating by electric field coupling.
In recent years, contactless integrated circuits operating by inductive coupling, or RFID integrated circuits, have considerably developed. Table 1 below summarises the characteristics generally found and/or standardised for this type of contactless integrated circuit.
TABLE 1main characteristics of RFID integrated circuitsOperating frequency: 13.56 MHz*Magnetic field radiation: WideData rate: 26, 106, 424, 847 Kbits/sClock signal extraction from the magnetic field: YesElectrical supply by induction (passive transponder): YesRead communication distance: up to 1 mWrite communication distance: up to 1 mOperational/working conditionsWater, rain: YesDirt, dust: YesHand carry: YesHuman body compatible: YesPresence of metal tolerated: Yes if d > 2-3 cm**Standards & accreditationExisting ISO standards: ISO 15693, ISO 14443ISO standards under definition: —USA accreditation: Yes, 3W***Europe accreditation: Yes, 3W***Japan accreditation: Yes, 3W****frequency of the magnetic field emitted by the integrated circuit scanner**distance between the antenna of the integrated circuit and the metal object***maximum power applied to the antenna circuit of the integrated circuit scanner
UHF integrated circuits are also known, the operation of which is based on the principle of an electric field coupling, and the main characteristics whereof are summarised in table 2 below.
TABLE 2main characteristics of UHF integrated circuitsOperating frequency: 433 MHz, 905 MHz, 2.45 GHz . . .Electric field radiation: Narrow and highly directionalData rate: 10-40 Kbits/sClock signal extraction from the electric field: NoElectrical supply by induction (passive transponder): YesRead communication distance: up to 4 mWrite communication distance: data write not providedOperational/working conditionsWater, rain: NoDirt, dust: YesHand carry: NoHuman body compatible: NoPresence of metal tolerated: No (reflections)Standards & accreditationExisting ISO standards: —ISO standards under definition: ISO 18000-6USA accreditation: Yes, 1 W**Europe accreditation: Yes, 500 mW**Japan accreditation: No*frequency of the electric field emitted by the integrated circuit scanner**maximum power applied to the antenna circuit of the integrated circuit scanner
One essential difference between RFID integrated circuits and UHF integrated circuits is that the latter cannot be carried by (or attached to) living beings (human beings, animals) and do not work in the presence of water or metal.
Furthermore, it is difficult to envisage writing data in passive-type UHF circuits (without any source of electrical power) since the electrical power that can be extracted from the UHF electric field is too low to generate a high voltage Vpp for erasing and programming an EEPROM or a FLASH memory.
In reality, it is possible in theory to write data but with a very short communication distance, or by adding a voltage source such as an electric cell. Now, in most applications, it is not possible to consider incorporating a voltage source into a UHF electronic tag that enables the memory to be written without restricting the communication distance, both for reasons of encumbrance and cost price and for reasons of product service life, such that most UHF integrated circuits are of the passive type.
Furthermore, it is not possible to extract a clock signal from the UHF signal for technological reasons (frequency too high to be applied to a frequency divider) and the synchronisation of the data transfer requires the use of special coding of the data (synchronisation signal included in the coding of the bit).
On the other hand, UHF integrated circuits offer communication distances that are much greater than RFID integrated circuits (see tables above).
Finally, UHF integrated circuits offer a relatively small scope of application due to the various above-mentioned restrictions of use but are particularly well suited to logistics applications (product monitoring and traceability) due to their high communication distance.
But as their memory cannot be written in normal conditions of use, it is not possible to write traceability data (such as indications of product storage place and date, indications about transit, etc. for example).